||This article needs attention from an expert on the subject. (March 2011)|
Cancer cells are cells that grow and divide at a rapid and unregulated pace. Although cancer cells are regularly created in the body, the disease known as cancer only occurs when immune cells (particularly natural killer cells) fail to recognize and/or destroy them.[not in citation given] In the past a common belief was that cancer cells failed to be recognized and destroyed because of a weakness in the immune system. However more recent research has shown that the failure to recognize cancer cells is caused by the lack of particular co-stimulated molecules, such as CD80, that aid in the way antigens react with lymphocytes.
Stem cell research suggests that too much SP2 protein MAY turn stem cells into cancer cells. Other issues thought to play a role in the spread of cancer include viruses, immune system issues, genetics, environment and age. However, a lack of particular co-stimulated molecules that aid in the way antigens react with lymphocytes can impair the natural killer cells' function, ultimately leading to cancer.
Cancer cells are created when the genes responsible for regulating cell division are damaged. Damage to DNA (mutations) can be caused by exposure to radiation, chemicals, and other environmental sources, but mutations also accumulate naturally over time through uncorrected errors in DNA transcription, making age another risk factor. This may eventually result in the rapid, uncontrolled growth characteristic of cancer cells.
Immune system cells, such as White Blood cells are thought to use a dual receptor system when they determine whether or not to kill sick, or damaged human cells. If a cell is under stress, turning into tumors, or infected, molecules including MIC-A and MIC-B are produced to put on the surface of the cell. These work to help the white blood cells to detect and kill cancer cells.
Some descriptions of cancer, not all descriptions, go back to ancient Egypt as far back as 1600 BCE and the understanding of cancer was significantly advanced during the Renaissance period. However, Sir Rudolf Virchow, a German biologist and politician, is generally credited with discovering the first cancer cells. As Giovanni Morgagni had linked autopsy findings seen with the unaided eye with the clinical course of illness, so Virchow correlated microscopic pathology.
Cancer cells have unique features that make them "immortal" according to some researchers. The enzyme telomerase is used to extend the cancer cell's life span. While the telomeres of most cells shortens after each division eventually causing the cell to die, telomerase extends the cell's telomeres. This is a major reason that cancer cells can accumulate over time creating tumors.
Cancer stem cells and drug resistance
Scientists have discovered a molecule on the surface of tumors that appears to promote drug resistance—by converting the tumor cells back into a stem cell-like state. When the tumor cells began to exhibit drug resistance, the cells were simultaneously transforming into a stem cell-like state, which made them impervious to the drugs. It appeared that the treatment itself was driving this transformation by activating a specific molecular pathway. Luckily, several existing drugs, such as Bortezomib for example, can attack this pathway and reverse the cellular transformation, thus ‘re-sensitizing’ the tumor to treatment.
- "The Innate Immune System: NK Cells". Community College of Baltimore County. Archived from the original on 2010-07-27. Retrieved 2010-12-01.
- Creating Cancer Killers. Research.uky.edu. Retrieved on 2010-12-01.
- Too much SP2 protein turns stem cells into 'EVIL TWIN' cancer cells. Sciencedaily.com (2010-10-27). Retrieved on 2010-12-01.
- What causes cancer? : Cancer Research UK : CancerHelp UK. Cancerhelp.org.uk (2010-07-15). Retrieved on 2010-12-01.
- The Adaptive Immune System: Ways That Antibodies Help to Defend the Body - Antibody-Dependent Cellular Cytotoxicity (ADCC). Student.ccbcmd.edu. Retrieved on 2010-12-01.
- History of cancer
- Cancer stem cells linked to drug resistance
- Tumor Cells Become Drug Resistant by Reverting to a Stem Cell-Like State
- Laetitia Seguin, Shumei Kato, Aleksandra Franovic, et al., & David A. Cheresh (2014). An integrin β3–KRAS–RalB complex drives tumour stemness and resistance to EGFR inhibition. Nature Cell Biology doi:10.1038/ncb2953
- BCG strain S4-Jena: An early BCG strain is capable to reduce the proliferation of bladder cancer cells by induction of apoptosis. Ncbi.nlm.nih.gov. Retrieved on 2010-12-01.
- The History of Cancer. Cancer.org. Retrieved on 2010-12-01